Revolving aircraft ski



June 28, 1960 Filed Aug. 15. 1955 3 Sheets-Sheet 1 /X D d 32 E n LQ /NvE/vToR 2Q ury j?. 72601261', ececzsed J Zfizza /ooz/ez; c/miz? 5241x1511 x Jf' www ATTORNEY June 28, 1960 c. R. HOOVER 2,942,808

REvoLvING AIRCRAFT sx1 Filed Aug. l5. 1955 3 Sheets-Sheet 2 J s, y Q

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, gaz/min @frat/fat "Bf" A7' 7' ORNEY June 28, 1960 c. R. HoovER REVOLVING AIRCRAFT SKI 3 Sheets-Sheet 3 Filed Aug. 15. 1955 N VENTOR ww, @Wm plv/.mh #im ,mmm D U w ATTORNEY United States Patent() REVOLVING AIRCRAFI` SKI curas R. Hoover, deceased, me of 9609 120th Ave., Edmonton, Alberta, Canada, by Christina Hoover, executrix, Edmonton, Alberta, Canada Filed Aug. 1'5, 1955, Sel'. No. 528,453

6 Claims. (Cl. 24th-10S) 'Ille invention herein relates vgenerally to aircraft landing apparatus and more particularly to an aircraft landing mechanism that may be changed selectively while the aircraft is in ight from wheels to skis or vice versa. The apparatus also includes improvements in mechanical movement which while particularly useful in conjunction with aircraft landing apparatus is also capable of other uses.

Prior mechanismsl for changing the landing apparatus of an aircraft so that either the wheels or the skis might be placed into position, depending upon the type of surface on which it was intended to land the aircraft, have included an eccentric crank arrangement manipulable to drop either the skis or the wheels into the lowered position attendant to the other being raised. Another selective landing mechanism has employed an opening in the ski through which the landing gear wheel may be depressed or raised when required. The above and other mechanisms have the disadvantage of requiring a large degree of skill on the part of an aircraft pilot to land his craft on the wheels without damaging the ski structure. This is caused principally by the fact that it is impossible to lower the aircraft wheels to any distance below the aircraft ski without unduly lengthening the undercarriage of the aircraft.

It is therefore the principal object of the present device to provide an aircraft landing mechanism wherein the aircraft ski is selectively revolvable to and from a position below the aircraft wheel.

An additional object of my device is to provide mechanism that will revolve the aircraft ski while the aircraft is in ight.

A further object is to provide apparatus of the aforesaid character having a minimum ofparts and that may be manufactured from readily obtainable low cost materials.

Additional objects and advantages of my device will become obvious to those skilled in the art on reading the following specification in the -lightof the attached drawings. It must be understood that the information disclosed therein is by way of illustration and example only and is not to be construed as a limitation.

In the drawings illustratin-gone preferred embodiment of my idea Fig. l is a fragmentary side elevational view illustrating an aircraft undercarriage modified in accordance with my device and showing the undercarriage in position for landingon skis. n I Y Fig. 2 is an end view projected on Fig. 1.

Fig. 3 is a fragmentary side 'elevationafview similar-V to Fig. l andillustrating the landing gear adjusted for landing on wheels.

Fig. 4 is an endviewprojected on Fig. 3.

Fig. 5 is a vertical longitudinal sectional view of the ski revolving mechanism embodying my invention.

Fig. 6 is a viewv of the right end of the mechanism illustrated in Fig.5. y

Fig. 7 is a view. of the left end of the mechanism illustrated in Fig. 5. Y

Fig. 8 is aview'smilar to Fig. 5 but illustrating the p lCe relative position of the movable elements when operated to revolve the ski degrees with respect to Fig. 5.

Fig. 9 is a view of the right end of the mechanism illustrated in Fig. 8.

Fig. 10 is an exploded side elevational view of the parts illustrated in Figs. 5 and 8.

Fig. l1 is a perspective view partly in section, illustrating the Yportions of the mechanism for attachment to the wheel yoke.

With continued reference to the drawings and particularly Figs. 1 through 4 there is shown in dot-dash lines one wheel 24 of an aircraft undercarriage leg 25. This wheel is jonrnallcd upon an axle 26 having one end mounted in the undercarriage leg. Straddling the wheel 26 is a U-shaped ski supporting structure or yoke 2. This U-shaped structure has the rear ends of its two legs nonrotatively mounted upon the axle 26 at opposite sides of the wheel 24 and projecting horizontally forwardly with respect to the aircraft (not shown). A plunger guide tube or inner cylinder 1 has a flange 20 upon its rearmost end secured to the Hat forward face of the U- shaped structure bight S1 by means of bolts (not shown) which respectively extend through holes 52, Fig. 1l, in the flange 20. A sealing O-ring 23 coaxial with the bore of the cylinder 1 Figs. 5 and 8, is disposed between the ange 28 and the bight 571 of the U-shaped supporting structure 2. Communication to the interior of such cylinder is provided rthrough a hose coupling member 21 .and a radial bore 53 in which the member 21 is mounted.

The forward end of the cylinder is communicated with by an L-shaped hose couplngmember 13 mounted in a closure end cap 12 of the cylinder.

A ski supporting member in the form of a mounting ring 9 is journalled co-axially about the cylinder 1 by means of a ball bearing unit 17'. The inner race of this ball bearing unit is secured to the cylinder 1 and prevented against axial movement thereon by a radial ange 18 and a nut l5 screwed onto the exterior periphery ofthe cylinder. A lock washer 16 is disposed between the nut 15 and the inner race of the bearing unit. A sealing ring 19 for the bearing 17 is disposed between the interior of a rear end portion of the ring 9 and the exterior of the cylinder 1. The ski supporting ring 9 has a mounting pad 54 for the attachment of one leg of a U-shaped spring member 11 by means of cap screws 55. 'Ilhe other leg of the spring member 11 has a ski 10, shown in dotdash lines, mounted thereon to extend substantially in parallelism with the principal axis of the cylinder 1 about which the mounting ring is rotatable for swinging or revolving the ski. A- portion of the ski 10 adjacent the wheel 24 has a wheel clearance notch 56 formed therein to diminish the radial distance that the ski can be mounted from the axis of the cylinder 1. When the ski is revolved about the axis of the cylinder 180 degrees counterclock- Va ski 10 and both skis will be raised to the position shown 4in Figs. 3 and 4 when making a normal landing upon :a

cleared landing strip.

When it is desired to land .the aircraft upon a surface of snow or ice the ski will be swung or revolved about the axis ofthe cylinder 180 degrees clockwise from the Fig. 4 position into the Fig. 2 position wmch :is also illustrated in Fig. 1. After the ski 10 has come into contact with the landing surface and the aircraft :imposes weight through the strut 25, axle 26 and the'supportingV stmcture 2, the force of this weight will 'flex the spring 11 and allow the lower side of the wheel'24 to bearupon that portion of the ski immediately'ftherebeneath'wherefore it `is unnecessaryV for the U-shaped structure 2 and Ythe spr-ing 11 to support the entire'weight of the aircraft. Means for selectively determining the operating position TVor theretracted upwardly swung position ofthe ski while Y `the"`airicr`aft` isf'in ilight includes aY tri-nodal plunger 3. `,This'pluiige comprises a forward cylindrical node Yor enlargement 57,V a center node '58 land a rear node (59. A

diametric-wrist pin 4 is mounted in the plunger'node 58 Y Lwhere :it isV anchored Vby a long' shanked set screw 5 pros jecting axially'into the plunger from its forward end. YOuter end portions' of the pin 4 project through respective mspiral slots 6 in the tube or plunger guide means 1 and Vinto respective spiral slots 7 of a tubularv driven camelernent`61 wheresth'ese outer end portions of the pin'constitutedriving velements for the driven element 61. The driven cam element y61 is rrotatively mounted upon the -eylind'er 1 and has a flange 8 upon its rearmost end secured to the ski mounting ringV 9 by cap screws 62. Thus the ski mounting ring 9 and the tubular driven cam element '61 are constrained for yrotation in unison wherefore this cam element can rotatively drivevthe ski mounting ring VVWhile'the latter holds -the cam element 61 against Vaxial movement. In a sense the element 61Y-is a tubular sleeve extension ,of the mounting ring 9, andthe cylinder 1 and the element 61, relatively to one another, are inner and outer cylinders. The ski supporting member or ring 9 in effect includes this outer cylinder. A tubular guard member`22 cooperates with a sealing ring 1K4 to contain -"lubricant'wln'ch otherwise would escape through the spiral "'slots6 and 7 onto exterior parts of the apparatus; The

- guard22 alsop'reventsY accidental loss of the pin 4 in the Y event of theY set screw 5 becoming loosened.

. strained for `rotation `with-the driven cam element 61, vthis retractivestroke of the plunger 3k is effective forrevolving this ski:10 from-its nonfoperative position shown l,in VVFigs., 3 Yand 4 toritsroperativeF position shownvinFigs. l

' In Fig.Y 1v0`it can be seenfthat the diametrically opposite Vspiral slots`V 6in the cylinderforfplunger Vguide tube 1 extend 90v degrees circumferentially of this tube. An

axially extending portion 27 is at the forward end of eachr of these slots and an axiallyextending ,endl portion 63 is at the rearward end of each thereof. The pitch Vdirection of these spiral slotsY 6 is such that the spiral sides react against the plunger-mounted pin 4 for causing clockwise rotation of the plunger as viewed from the front end of the'tubular member 1 attendant to the plunger and pin V4'being moved axially rearwardly in such tube, that is, 'rightward as viewed in Figs. 1, 3 and 10. Movement of the plungerl 3 forwardly through a complete stroke from `the retracted position where the pin end portions are in 'the slot end portions 63 until they are disposed within f the slot end portionsv 27 causes the plunger to rotate 90 degrees counterclockwise, whereas complete retraction of fthe plunger for again disposing the ends of the pin 4 in the slot endrportion 63 causes a retractive 90 degree rota-tionrof such Yplunger clockwise. Forward motion of the vl'alunger 3 is-incurred by. introducing iiuid, preferably Aoil, under. pressure through the hose coupling 21 into fthe rear end ofthe tube 1 while exhausting iiuid from the forward end of theitube through the hose coupling 13.1 Retractive Yaxial movement ofjlthe plunger is accomplished Vby reversing the flow of uid to force such VVuid Vunder pressure into the left end of the tube through Y Vvthehose coupling 13 while Yexhausting iluid from the VArightror rear endrof the tube from the hose coupling 21. f Referring again towPig. l0, it can be seen that the spiral slots 7 'of which the sides constitute a helical cam fprole for thefcarn driven element 61 also extend 90 degrees' circumferentially of such driven camelement. However, .theV pitch direction of these cam proiiles is oplp'o'site to that of the slots 6in the cylinder 1. ThatL is,

Ythe 'cam slots or profiles 7 Yprogress counterclockwise aboutthe tubular driven cam element 61 as viewed from i .Y the left end thereof as they progress rearwardly from horizontal'end portions `64 thereof to horizontal rear end portionsv 65 thereof, whereas the slots y6 progress clock- Wise -as they extend rearwardly' from the horizontal for- "ward endportions 27 to the rearward horizontal end portions 163.. Y Therefore assuming that the plungerr 3 is pin 4 are in* the end portions'27 of the slots'tand'inthe end portions 64 of the cam prole slots 7, retractive movement of the plunger will cause the pin 4 to react against the sides of slots 6 for causing clockwise 90 degree rotation ofrthe plunger attendant to a full stroke retractive motion carrying the pinfii'ntothe slot end portions 63. Since the pin end portions are alsodisposed within the driven cam member slots 7',n this l9,0 degree revolving motion of the pin' endp'ortions"impartsV ar90'de'greecomponentV of lrotative''movementv to the driven element 61. Also since the driven `Aca'rnelelilenttl'is'iestrained against axial movement, Vthe rearward 'lineari component of movement of the pin 4 causes camming action of its end portions' againstthe side of the profiler slots 7 for imparting an additional degree component of rotative movement to the driven cam element 61, wherefore attendant to a complete retractive stroke ofthe plunger the driven camrelement 61` will be rotatedV 18() degrees clockwise. Since Vthe -ski mounting ring` Q and theski 10jareconand 2. When itisfdesired tojagain swing the ski from its operative position of Y `Figs, l and 2 to its non-.operative positionfof IFigsuS 4- fluid will ibeintroduced (nto the v rear end ef themeerlthotigh the nose oupungrzrfor protr/acting (ther plunger 3 forwardly a complete stroke whereupon helical slots 6 in the tube 1 cause4 acounterclockwise rotation of theplunger QOjdegrees causing the outer ends ofthe plunger` pin 4to cooperatewith the complemental cam slots A'7o f ,the` drivencamimember 61 forv `imparting V1870 degreesbrotationto this driven Vcam memberand thereby swing {the ski `18() degrees counter- Yclockwisevasviewecl, in vFig. 2 to theretracted` position While the. endA portions ofV pin y4 Vare disposed in Ythe Vforward end portions'27 of thevslots -6 andthe forward endV portions 64Mof`the campslots 7, these pin'end portions are elective for Vlocking the cam elements 61 and the 'ski 10 against movement about the axis of theV tube 1 without the need' of significant'uid pressureacting' upon the plunger 43. Y Similar lockingfofV the carn element 61"' and the ski against movement about thet'axris of ,tubel occurs whenr'thezend'I portions of pin 4 arefdisposedintherrear end portionsj63 and -65 o'thejslots '6 and7.

Having described a single preferred embodiment ofthe invention, With'the view Vand conciselyY illustratingY the saine,` what is claimed "is:

1. ,The combination with as'wheeled undercarriagefor aircraft; aircraft landing'skis; meansflorV mounting such skis onto the wheeled undercarriage"comprisingyinner cylindersy rotatively Vandfaxially ixed'tothe-undercarriage respectively Yadjatent -the wheelsfwith `the axisfof Veach vcylinder .arranged horizontally and radially of its lassociated wheel, driven cam -elementsV-iny-theform `-of .I outerY cylinders respectively-mounted*rotatively onlthe innercylinders means constrainingthe Voutercylinders against axial-movement, thel innerpylinders 'having spiral Aslots Vextending axiallyof their-'side walls and vspirally about the cylinder axes, the 'outerl cylinders having' spiral slots like those-of the finner 'cylinderspbuti of'whichthe pithis Voppositegto that pfthe inner cylinder slots'g-and means for securing 'the' skis respectively von Ythe.V outer v tive oscillative rotation Lvof the outerV cylindersiand `means for locking the skis in position selectively above and below the wheels.

2. The combination set forth in claim 1, wherein the means for locking the skis selectively above and below the Wheels comprises end extensions of the cylinder slots and which extensions depart from the spiral formation to extend substantially axially of the cylinders, and the extensions at corresponding ends of the slots being receptive of the pins to hold the cylinders against relative rotation.

3. In combination with ari aircraft undercarriage including a landing wheel; a supporting structure mounted on the undercarriage adjacent said wheel; a ski supporting member carried by said supporting structure and oscillatable about an axis of such member extending fore and aft of the aircraft, said axis also extending radially of and intersecting the wheel; a plunger device comprising a plunger guide tube mounted on the supporting structure co-axially of said supporting member axis and constrained by Said supporting structure against rotation about such wis, and a plunger movable axially in said tube, the tube having a side wall slot extending helically about said axis in one direction of pitch; a driving cam element mounted on the plunger and projecting radially thereof through said slot and guided by the slot to move in a helical path coincident with said slot attendant to axial movement of the plunger; a driven cam element mounted rotatively upon the plunger guide tube; and means coustraining the driven cam element against movement axially of the tube and such driven ca m element being connected with the ski supporting member for rotating the l latter therewith, the driven cam element containing a helical cam profile extending about the tube axis in the opposite pitch direction to that of the tube wall slot, and said profile being receptive of the driving cam element to impart rotative movement to the ski supporting structure attendant to both the axial and rotative components of the helical motion of such driving element.

4. In combination with an aircraft under-carriage including a landing wheel, a supporting structure mounted on the under-carriage adjacent said wheel, a plunger guide cylinder mounted non-rotatively and constrained against axial movement upon -said supporting structure and projecting horizontally radially of said wheel within the plane thereof, said cylinder having a side wall slot extending helically therein in one pitch direction, a plunger reciprocally mounted in said cylinder and having a pin projecting radially therefrom outwardly through said slot, a ski supporting member mounted rotatively about said cylinder and having a sleeve extension projecting coaxially about the cylinder in registry with said slot, the sleeve extension having a slot extending helically therein in the opposite pitch direction of the cylinder slot and also receiving a section of said pin, means for selectively conducting Huid under pressure into opposite ends of the cylinder to force said plunger endwise therein attendant to the cylinder slot co-acting with the pin for rotating such pin and' the plunger co-axially of the cylinder, and for causing the rotating pin to co-act -with the slot in the sleeve extension for imparting additional rotative motion to the ski supporting member.

5. In combination with an aircraft undercarriage in= cluding a landing wheel; a ski supporting structure mounted on the undercarriage adjacent said wheel and in alignment therewith in a fore and aft direction, said supporting structure including bearing means having an axis extend-y ing fore and aft of the aircraft within the plane of the wheel, said supporting structure also including a ski supporting member mounted on the bearing means and oscillatable thereon about said axis, said ski supporting member being spaced from the wheel lengthwise of such axis; a ski mounted solely on such supporting member to extend in parallelism with said axis and spaced radially rom such axis a distance to occupy positions respectively contiguously above and below the wheel attendant to oscillative adjustment of the supporting member selectively between positions spaced aboutv said axis, the ski having a wheel-engageable portion disposed beneath the Wheel when the ski is below such wheel, and the ski supporting structure possessing resiliency to facilitate deection thereof by the Weight of the aircraft to press the wheel downwardly onto said wheel engageable portion of the ski while the ski is in contact with a landing surface. 6. The combination set forth in claim 5, wherein the ski supporting structure comprises an 4inner cylinder coaxial with said fore and aft axis, wherein the ski -supporting member includes an outer cylinder mounted coaxially on the inner cylinder and oscillatable thereon, wherein there is ski mounting means on the outer cylinder, and wherein there is means for oscillating the outer cylinder and such ski mounting means.

References Cited in the file of this patent UNiTED STATES PATENTS 977,288 Euchenhofer Nov. 29, 1910 1,079,201 Wise Nov. 18, 1913 1,101,458 Levoy June 23, 1914 1,128,698 Levy Feb. 16, 1915 1,805,914 Larsen May 19, 1931 1,946,309 Coffman Feb. 6, 1934 2,237,970 Pabst Apr. 8, 1941 2,247,562 Santen July 1, 1941 2,636,289 Pryor Apr. 28, 1953 FOREIGN PATENTS 223,618 Great Britain Oct. 24, 1924 

